Peruvian Booby

Fascinating facts about the Peruvian Booby

• When the 1950s rolled around, the Peruvian booby swelled to about 3 million individuals, making it the most abundant seabird along the Peruvian coast and the second biggest guano producer, showing how a single species can shape an entire coastal economy.
• Female Peruvian boobies are on average 19 % heavier and have wings about 4 % larger than males.
• These birds plunge into the water for just 3.1–3.4 seconds, rarely diving deeper than 4.3 metres, yet they spend 90 % of their foraging time soaring above the sea, demonstrating a hunting style that relies on speed and vision rather than deep dives.
• The average speed of the Peruvian booby is about 44 km/h, and it can reach speeds up to 139 km/h.
• Hybrid offspring most often arise when a female Peruvian booby mates with a male blue-footed booby; the two species diverged 0.25–0.45 million years ago.

At a glance

About the Peruvian Booby

The Peruvian booby (Sula variegata) cuts a striking figure against the misty horizons of the Humboldt Current, its brown upperparts contrasting with a crisp white head and underparts, while the wings display a distinctive white-mottled, scale-like pattern along the wing-coverts. A long, pointed grey bill and grey webbed feet set it apart from its blue-footed and red-footed cousins, and females tip the scales, averaging 19 % heavier and boasting wings 4 % larger than the males. These sleek seabirds nest on smooth, windswept sand flats, pampas, where temperatures hover between 28 °C and 38 °C, forming dense colonies on islands such as Lobos de Tierra and Lobos de Afuera, a testament to the species’ adaptation to the coastal upwelling that fuels their world. Life for the Peruvian booby is a study in efficiency: they are plunge divers, typically plunging for just 3.1–3.4 seconds to depths of 2.3–4.3 m, often within five kilometres of their nests, though some have been recorded as far as 40 km offshore. Their diet is dominated by Peruvian anchoveta, with mackerel added when prey abundance shifts, and their foraging trips last only a few hours, spending 90 % of the time airborne. A surprising trait lies in their vocal repertoire, females emit trumpet-like quacks and honks, while males whistle, a unique adult communication that only matures after several years. Their glide-flapping flight, averaging 44 km h⁻¹ but capable of bursts up to 139 km h⁻¹, lets them skim the wind across the coast, balancing energy use with prey encounter rates as they raise one to four pale-blue eggs each breeding season.

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